For most of enterprise storage solutions, multipath approaches are introduced to support high availability of the storage system. The multipath approaches are used to provide a path redundancy solution for a storage device with a backup access path. As used herein, terms “access path,” “I/O path” or “path” generally refers to input output I/O paths including various components of a storage device, such as an I_T nexus model in a small computer system interface (SCSI) architecture. For example, for a serial SCSI (SAS) domain based storage product, an access path may include a host bus adapter (HBA) card, an SAS expander, a target driver, and so on.
A main problem in existing multipath solutions is their path heath diagnosis methods which only focus on one aspect of error information, such as SCSI error information at a lower layer. However, a single aspect of error information is often insufficient (or not intelligent enough) to help make a good path related strategy. Thus, the existing multipath solutions are unable to make efficient and accurate path health diagnosis and hardly meet performance requirements of a storage system.